Abstract: A DNA sequence encoding a transport protein responsible for the physical movement of oxalate and formate across the plasma membrane is provided. The protein, OxlT, can be isolated from the gram negative anaerobe, Oxalobacter formigenes. The protein is part of the three protein oxalate/formate antiport exchange system that allows for conversion of extracellular oxalate to formate+CO.sub.2.The OxlT coding sequence can be used to provide a metabolic energy system to the cell. The system comprises the OxlT transport protein in combination with oxalylCoA decarboxylase and formyl-CoA transferase. Expression cassettes can be designed to express all or part of the system in a target host. Such energy generating systems can be used in industrial settings that utilize fermentation. The energy generating systems of the invention extend culture longevity and increase product yield.